For instance, for an internal combustion engine of a vehicle, in order to prevent release of fuel vapor evaporated from a fuel tank of the vehicle into the outside, a canister that is capable of adsorbing and desorbing the fuel vapor is provided. As is known, an inside of a case of this canister is filled with an adsorbent. An air release opening is provided at one end side in a flow direction, and an inflow portion (a charge port) of the fuel vapor which communicates with the fuel tank and an outflow portion (a purge port) of the fuel vapor which communicates with an intake passage of the internal combustion engine are provided at the other end side in the flow direction. The fuel vapor that is generated after vehicle stop etc. is introduced into the canister from the fuel tank through the inflow portion, and is temporarily adsorbed by the adsorbent. Subsequently, during vehicle travelling, a flow of air where atmospheric air flows into the canister from the air release opening and flows out of the canister from the outflow portion by an intake cycle of the internal combustion engine occurs, and by this air flow, a fuel component adsorbed by the adsorbent is desorbed together with a fresh atmospheric air, and is introduced into a combustion chamber from the outflow portion through the intake passage of the internal combustion engine, then is burnt in the combustion chamber.
To efficiently perform the adsorption and desorption in such a canister, for instance, Patent Document 1 discloses a canister in which a plurality of chambers filled with the adsorbent are arranged in series along the air flow direction in a case of the canister, and a chamber located at an air release side is filled with an adsorbent that has high heat capacity.
Further, in Patent Document 2, as a technique of greatly reducing a diurnal breathing loss emission (Diurnal Breathing Loss; DBL), the adsorbent filling the canister is classified into two kinds of activated carbons of an activated carbon (hereinafter called A-carbon) whose difference of an equilibrium adsorption amount of n-butane concentration between vapor concentrations of 5 vol % and 50 vol % n-butane is greater than 35 g n-butane/L and an activated carbon (hereinafter called B-carbon) whose difference is less than or equal to 35 g n-butane/L, then a chamber located at an inflow and outflow portion side is filled with an adsorbent using the A-carbon and a chamber located at an air release side is filled with an adsorbent using the B-carbon. In this manner, by disposing, at the air release side, the activated carbon whose difference of the equilibrium adsorption amount is small, i.e. by disposing, at the air release side, the B-carbon which, although an effective adsorption amount (a difference of the adsorption amount between at the adsorption and after the desorption) is small, has an excellent desorption performance, emission of the fuel vapor to the air release side is suppressed, and the diurnal breathing loss emission (DBL) is reduced.